Shale oil refining process using a selective solvent and anhydrous hydrogen chloride



9 c. N. KIMBERLIN, JR., ETAL 2,956,450

SHALE OIL REFINING PROCESS USING A SELECTIVE SOLVENT AND ANHYDROUSHYDROGEN CHLORIDE Filed April 25, 1958 3o HYDROGENATOR SETTLER SOLVENTHCI L.

sHALE Charles Newton Kimberlin, Jr Henry George Ellert Inventors ByWuMAttorney ite SHALE OIL REFINING PROCESS USING A SELEC- TIVE SOLVENT ANDANHYDROUS HYDROGEN CHLORIDE Filed Apr. 25, 1958, Ser. No. 730,897

7 Claims. (Cl. 20810) The present invention relates to the refining ofshale oil. More particularly, the present invention relates to a methodfor improving the characteristics of charging stocks from shale oil foruse in catalytic cracking processes while minimizing the loss ofsuitable cracking feed stocks.

Shale oil as produced by retorting of oil shale contains only a minorproportion of materials suitable for use directly in motor fuels withoutprocessing and chemical conversion. An important problem in the use ofshale oil for the customary conversions to which petroleum oils arenormally subjected is the excessive coke formed when the oil issubjected to catalytic cracking.

Shale oil cannot be satisfactorily refined by standard petroleumprocessing techniques chiefly because of its high nitrogen content,amounting to about 2%, and its low carbon to hydrogen ratio, and highsulfur content. Only about 20 to 25% of the oil is aliphatic; possiblyover 50% is composed of compounds containing nitrogen, oxygen andsulfur.

Considerable Work has been done in attempting to separate undesirablefrom desirable components of shale oil by a variety of treatments, fromthermal soaking, visbreaking, to extraction with liquid solvents.However, those solvents which removed undesirable nitrogenous materialwere unselective and removed desirable cracking constituents as Well.Thus liquid S liquid ammonia, various organic solvents, strong acidssuch as H 80 weak acids such as H 80 and acetic or formic acids have allgiven unsatisfactory results, either because of ineffectiveness or poorselectivity.

It is an important object of the present invention to provide animproved method for the upgrading of shale oil. It is a further objectof the present invention to produce from shale oil feed stocks ofimproved quality for catalytic conversion thereof into motor fuel andother valuable hydrocarbons while minimizing the loss of suitablecracking material.

The foregoing and other objects and advantages of the present inventionwill be more clearly understood from the detailed description of theinvention, made with reference to the accompanying drawing, which represents diagrammatically a preferred method for carrying out theinvention.

In accordance with the present invention it has been found that shaleoil is effectively upgraded by treatment withan acidic gas in thepresence of a hydrocarbon solvent under certain conditions discussedhereinafter. There is obtained a sludge or precipitate representingsubstantially all of the more undesirable coke-forming nitrogencontaining constituents; this sludge nonetheless being extremely smallin amount. There is further obtained as an extract a maximum amount ofhigh quality cracking stock.

Turning now to the drawing, raw shale oil obtained by retorting oilshale at a temperature of about 800 to 1200 F. for a period of 0.1 to 2hours is fed by means of line 2 to precipitation zone 4. Though theshale oil tates Pater may be given a preliminary thermal treatment orsubjected to visbreaking conditions, this is normally not necessary. Infact, it is one of the advantages of the present invention that thevisbreaking operation may be dispensed with. Zone 4 may be an uprightvessel provided with means for providing intimate contact ofcounterflowing streams, such as agitators, packing, perforated platesand the like. Alternately, vessel 4 may be a mixer-settler ofconventional design. The shale oil is treated in vessel 4 with fromabout 0.5 to 10 volumes of a hydrocarbon fraction boiling in the rangeof from -45 to 250 F. Pentane, hexane, propane, butane or naphthafractions give good results. This hydrocarbon is introduced through line5. The temperature is in the range of 0 to 300 F., preferably 50 to F.,and pressure sufiicient to keep material in the liquid phase. In furtheraccord with the present invention, an anhydrous acidic gas, such as HCl,HBr, BF and the like, but preferably HCl, is passed into vessel 4through line 7 in amounts suflicient to saturate the oil. 0.5 to 4.0,but preferably 0.9 to 1.5, equivalents of acid per equivalent ofnitrogen in the oil may be used. The oilsolvent-gaseous acid mixture ismaintained in a state of agitation, preferably for a residence period offrom about 1 to 60 minutes, and then passed to settling zone 8. Theextract, containing the oil and solvent, is removed from zone 8 throughline 10 to flash distillation zone 12, Where the low boiling hydrocarbonsolvent is dis tilled overhead by flash or fractionation and recycledvia line 14 to precipitation zone 4. The shale oil fraction may thenadvantageously be passed to a catalytic cracking zone 18 for conversionby conventional means into valuable fuels and lubricants.

It is to be understood that, although in the above description, solventprecipitation and acid gas treatment were indicated as taking placeconcurrently, it may often be preferable to complete the solventprecipitation prior to the addition of the acid gas. The latter schemecould be advantageously applied where relatively pure amine salts arethe desired by-product.

Returning now to settler 8, the lower layer is a sludgelike materialcomprising in part high molecular weight hydrogemdeficient materialknown as Conradson carbon, and also the salt-like reaction product ofthe HCl and the nitrogen compounds. About 7 to 15 lbs. of HCl per barrelof oil are required in this process.

This low quality sludge, amounting to some 25 to 35% of the total shaleoil, may also be utilized to increase the over-all yield of motor fueland lubricants. In one embodiment of the invention, it is withdrawn as alower layer from vessel 8 and passed to a hydrogenation zone 30. Byoperating at about 3,000 p.s.i.g. in a conventional manner and at 650 to1000 F., preferably 700 to 850 F., the nitrogen content of the sludge isreduced from 5% to 0.5% or less. Alternately, this sludge may bepartially hydrogenated at less severe conditions and the productrecycled through the precipitation zone.

In still another embodiment of the invention, the salt sludge is passedvia line 46 to treating zone 40 for HCl recovery. In zone 40 the saltsludge is heated to 250 to 400 F. or higher and a purge gas streampassed in through line 42. The gas may be an inert gas, N CO a lowboiling hydrocarbon or steam. At these temperatures the salt sludgedissociates into the free amines and hydrogen chloride, the latter beingwithdrawn with the purge gas through line 44. The HCl-rich purge gas isseparated for recovery by conventional means, and the recovered I-IClmay be recycled to shale oil treater 4 through line 44. Preferably,vapors of the solvent used in the process comprise the purge gas stream,and in this situation the HCl-rich stream is recycled to theprecipitation zone without separation.

Example 1 A sample of shale oil was treated in accordance with theprocess described in the presence of n-hexane. Four types of acidictreating agents were employed, with the result shown below:

1 4 mols/mol N; in oil.

These data clearly demonstrate the excellent results obtained by theprocess of the present invention in upgrading shale oil to a catalyticcracking feed stock. It is to be noted that aqueous acid provides asubstantially lower oil yield without quality improvement.

Example 2 The necessity of maintaining a solvent in the mixture beingacid treated with gaseous HCl is shown by the following data:

Treatment None N 01 H crane-l- 400 F. HCl

Yield, Vol. Percent 67 70 PlOdJCt finality:

ravi y, PI 20. 6 Nitrogen, Wt. Percent 1. 9 3:4 Con. Carbon, Wt. Percent4.3 3. 9 0.9

1 Added to saturation.

Example 3 The oil prepared as in Example 1 from hexane and HCl wastested as a catalytic cracking feed stock. Reactor conditions included atemperature of 900 F., atmospheric pressure, a feed rate of 2v./v./hour, a half hour cycle, and fresh alumina-silica crackingcatalyst.

Raw Hexane East Feed Shale H Cl- Texas Oil Treated Liglt Gas 011Conversion (OTC) 40. D+L 1 vol. Percent) 29. 1 it? Dry Gas (Wt. Percent)9.4 11.2 14.4 Carbon (Wt. Percent) 11.3 5. 4 4. 7

1 Distillate plus loss.

These data show the substantial equivalency of the treated shale oilwith the high quality East Texas Light Gas Oil.

Example 4 Shale oil sludge may be hydrogenated to give an upgradedproduct. Here a cobalt m0lybdateAl O catalyst was employed at 3000p.s.i.g. H pressure. The effect of temperature is pronounced.

Process Temper- Crudo ature Product Quality Sludge Gravity, API... 2.58.3 32. 0 N Wt. Percent" 5.0 2.6 0. 5 S, Wt. Perceut 0.5 0. 4 0.05

Alternately, it may be advantageous to subject this sludge to lowerseverity hydro-processing, such as hydrotreating at 500 to 1000 p.s.i.g.to form lower molecular weight amines while recovering a part of thenitrogen as N or NH followed by recycle of the product to theprecipitation zone.

What is claimed is:

l. A process for treating a crude shale oil containing substantialamounts of nitrogenous constituents and Conradson carbon which comprisesagitating said oil with about 0.5 to 10 volumes of a selectivehydrocarbon solvent boiling in the range of -45 to 250 F. at atemperature and pressure to maintain said solvent and oil in a liquidstate, saturating said mixture with an anhydrous gaseous hydrogenchloride in the amount of about 0.5 to about 4.0 equivalents of acid perequivalent of nitrogen in said shale oil, separating a solvent layerfrom a sludge layer, and recovering a high quality catalytic crackingfeed stock from said solvent layer.

2. An improved process for recovering valuable hydrocarbonaceousproducts from crude shale oil containing substantial amounts ofnitrogenous constituents and Conradson carbon which comprises passingcrude shale oil to a first treating zone, passing about 0.5 to 10volumes of a selective hydrocarbon solvent boiling in the range fromabout -45 F. to about 250 F. to said zone, agitating said mixture in thepresence of a saturating amount of gaseous anhydrous hydrogen chlorideat a temperature in the range from about 50 F. to about F., saidanhydrous gaseous hydrogen chloride being present in the amount of about0.5 to about 4.0 equivalents of acid per equivalent of nitrogen in saidshale oil, separating an oil and solvent layer from a sludge layer,separating solvent from said oil and passing at least a portion of saidseparated solvent to the first treating zone, passing said oil to acatalytic cracking zone, passing said sludge layer to a second treatingzone and recovering valuable products from said second treating zone.

3. The process of claim 2 wherein said sludge layer is hydrogenated atelevated pressures of 500 to 3000 p.s.i.g. and temperatures of 650 to1000 F. in said second treating zone and thereafter mixed with thetreated oil prior to its passing into the catalytic cracking zone.

4. The process of claim 2 wherein said sludge layer is heated to atemperature in the range of about 250 F. to 400 F. in said secondtreating zone, purging with vapors of the selective hydrocarbon solventthe liberated HCl from said second treating zone, and passing themixture of said gases into the first treating zone.

5. The process of claim 4 wherein said treated sludge layer is furthertreated by hydrogenation at elevated pressures of 500 to 3000 p.s.i.g.and temperatures of 650 F. to 1000 F. in a third treating zone andthereafter mixed with the treated oil prior to its passing into thecatalytic cracking zone.

6. The process of claim 2 wherein said sludge layer is hydrogenated in asecond treating zone at a hydrogen pressure of about 3000 p.s.i.g, atemperature of about 750 F. and in the presence of a cobalt molybdatc-AlO catalyst and thereafter mixed with the treated oil prior to itspassing into the catalytic cracking zone.

7. An improved process for recovering valuable hydrocarbons from shaleoil sludge produced by the treatment of the shale oil with anhydrous HClin the presence of a low boiling hydrocarbon solvent which comprisessubjecting said sludge to a hydrogenation reaction at a hydrogenpressure of about 3000 p.s.i.g., a temperature of about 750 F. and inthe presence of a cobalt molybdate-Al o catalyst.

References Cited in the file of this patent UNITED STATES PATENTS ThomasJune 27, 1944 Castner et a1 Dec. 15, 1953 Wetzel Mar. 22, 1955 HughesNov. 5, 1957

1. A PROCESS FOR TREATING A CRUDE SHALE OIL CONTAINING SUBSTANTIALAMOUNTS OF NITROGENOUS CONSTITUENTS AND CONRADSON CARBON WHICH COMPRISESAGITATING SAID OIL WITH ABOUT 0.5 TO 10 VOLUMES OF A SELECTIVEHYDROCARBON SOLVENT BOILING IN THE RANGE OF -45* TO 250*F. AT ATEMPERATURE AND PRESSURE TO MAINTAIN SAID SOLVENT AND OIL IN A LIQUIDSTATE, SATURATING SAID MIXTURE WITH AN ANHYDROUS GASEOUS HYDROGENCHLORIDE IN THE AMOUNT OF ABOUT 0.5 TO ABOUT 4.0 EQUIVALENTS OF ACID PEREQUIVALENT OF NITROGEN IN SAID SHALE OIL, SEPARATING A SOLVENT LAYERFROM A SLUDGE LAYER, AND RECOVERING A HIGH QUALITY CATALYTIC CRACKINGFEED STOCK FROM SAID SOLVENT LAYER.